In a conventional mobile communication system, in an uplink communication n from a mobile station UE to a base station Node-B, a radio network controller RNC determines a transmission rate of a dedicated channel in consideration of a radio resource of the base station Node-B, an interference amount in such an uplink communication, transmission power of the mobile station UE, transmission processing performance of the mobile station UE, a transmission rate required by an upper-level application, and the like. Then, the radio network controller RNC notifies the determined transmission rate of the dedicated channel individually to the mobile station UE and the base station Node-B by a message of the Layer 3 (Radio Resource Control Layer).
Here, the radio network controller RNC is an apparatus that is located at an upper level of the base station Node-B, and controls the base station Node-B and the mobile station UE.
In general, in the data communication, it is more frequent that traffic occurs in a bursting manner than in a voice communication and a TV telephone communication, and it is primarily desirable to change a transmission rate of a channel for use in the data communication at a high speed.
However, as shown in FIG. 1, the radio network controller RNC usually controls many base stations Node-B in a centralizing manner, and accordingly, in the conventional mobile communication system, there has been a problem that it is difficult to perform such a high-speed (for example, at approximately 1 to 100 ms) change control for the transmission rate because of the reasons such as a processing load and a processing delay.
Moreover, in the conventional mobile communication system, even if the high-speed change control for the transmission rate of the channel can be performed, there has been a problem that implementation cost of the apparatus and operation cost thereof are increased to a large extent.
Therefore, in the conventional mobile communication system, it is usual to perform the change control for the transmission rate of the channel in several hundred-millisecond to several-second orders.
Hence, in the conventional mobile communication system, in the case of performing a bursting data transmission as shown in FIG. 2(a), the data is transmitted as shown in FIG. 2(b) while permitting a low speed, a high delay, and low transfer efficiency, or the data is transmitted as shown in FIG. 2(c) while ensuring a radio resource for a high-speed communication and permitting waste of a radio bandwidth resource and a hardware resource in the base station during an open time.
Note that, in FIG. 2, both of the above-described radio bandwidth resource and hardware resource apply to a radio resource of an axis of ordinates.
In this connection, in the “3GPP” and the “3GPP2” which are the international standardization organizations of the third-generation mobile communication system, there has been studied a high-speed radio resource control method in the layer 1 and the MAC sub layer (layer 2) between the base station and the mobile station for the purpose of effectively utilizing the radio resource. Hereinafter, such a study and a function thus studied will be generically referred to as “Enhanced Uplink”.
In the Enhanced Uplink, the base station Node-B controls the transmission rate of the channel for use in the uplink communication in lower-level layers (layer 1 and layer 2), thus making it possible to increase a throughput of a cell.
Specifically, as shown in FIG. 3, the base station Node-B is configured to measure a noise rise of the channel for use in the uplink communication, and to sequentially control the transmission rate of the channel so that the noise rise of the channel can converge to a level approximate to a maximum allowable noise rise.
Here, the noise rise is a ratio (received signal level from a noise floor) of interference power in a predetermined channel within a predetermined frequency and noise power (thermal noise power and noise power from the outside of the mobile communication system) within the predetermined frequency.
Note that, in this specification, a channel to which the Enhanced Uplink is applied will be referred to as an “enhanced channel” (for example, a dedicated channel to which the Enhanced Uplink is applied will be referred to as an “enhanced dedicated channel”), and a channel to which the Enhanced Uplink is not applied will be referred to as a “non-enhanced channel”).
Moreover, the enhanced channel is usable while being present mixedly with a conventional channel such as a circuit switching channel, a dedicated physical control channel (DPCCH), and an uplink control channel for controlling a downlink network.
In the uplink communication in the conventional mobile communication system (especially, a mobile communication system that adopts the CDMA system), call acceptance control processing is performed by using the noise rise in addition to a hardware resource of the base station Node-B.
Meanwhile, in a downlink communication in the conventional mobile communication system, the call acceptance control processing is performed by using total transmission power of the base station Node-B in addition to the hardware resource of the base station Node-B.
Specifically, in the uplink communication in the conventional mobile communication system, when the hardware resource of the base station Node-B is sufficiently present in comparison with a capacity of a radio bandwidth resource, the call acceptance control processing is performed by the noise rise (specifically, it is determined whether or not a new channel is to be set).    (Non-Patent Document 1) “W-CDMA Mobile Communication System” published by Keiji Tachikawa, Jon Wiley & Sons
However, in the conventional mobile communication system, the transmission rate of the channel for use in the uplink communication is controlled so as to always increase the noise rise to the maximum allowable noise rise when the Enhanced Uplink is applied. Accordingly, there has been a problem that highly accurate call acceptance control processing becomes difficult.
Moreover, there has been a problem that, though the enhanced channel is a channel for use in a best effort data communication, and in usual, priority thereof is lower than that of a circuit switching communication of voices, real-time moving pictures, and the like, there can occur a state where the noise rise is occupied by the enhanced channel, resulting in that a circuit switching call cannot be accepted (specifically, the circuit switching channel cannot be set).